Windows 7 - DDR3 compatability question

Hello all,

I just want you to confirm that I am not making a purchasing mistake.

My mobo, ASRock M3A770DE, Supports DDR3 1600(OC)/1333/1066/800 non-ECC, un-buffered memory. It currently has 1 4gb stick of Corsair Vengeance 4GB (1x4GB)1600MHz DDR3 PC3-12800 RAM.

I wish to add 2 more 4gb sticks of Corsair 8GB (2x4GB) DDR3 1600MHz XMS3 Memory (source ebay - Corsair 8GB (2x4GB) DDR3 1600MHz XMS3 Memory Kit BOXED | eBay UK).

Can someone please confirm this would be ok, even though it additionally says XMS3?

Thank you in advance.

The Vengeance runs at 1.5v and the XMS3 runs at 1.65v so it may be a problem getting them both to run at 1600 CL9 as rated.

Jim

1 would buy another 4gb stick of Corsair Vengeance 4GB (1x4GB)1600MHz DDR3 PC3-12800 RAM. This way you will not run into any issues and I will run in duel channel. Just make sure the full part number are the same. Corsair makes alot of revitions.

Phoneman/Beta,

you have both taught me something in terms of voltages and dual channels. I am now inclined to buy Corsair Vengeance DDR3 memory (2x4GB) | eBay UK based upon what you have now told me.

Thanks

I assume you are running Windows 7 64bit as 32bit wont see anything over 4GB.

I would go with this one. I think it is the same you have now and you would then have 1 stick in each channel. Three sticks would not be the best solution as AMD CPUs have shown problems with more than 2 sticks of memory especially at speeds above 1333.

Corsair CMZ4GX3M1A1600C9 4GB 1600MHzCL9 DDR3 Vengeance | eBay UK

Jim

If wanting to go with dual-channel, I would buy both modules as a matched kit, as they would then be certified to work correctly together. Even seemingly identical modules (same model/manufacturer) may or may not work correctly together if purchased separately. See DDR2 Memory Issues Affecting System Reliability for a similar thread on the subject.

Hi phoneman,

Thanks for your advice, I want to buy two of the items you suggest, taking me upto a total of 12gb. Ultimately i will goto 16gb when i can afford it, as the board states it can go that high. What is this about problems above 8gb at speeds above 1333? Could i potentially change the ram speed of the 12gb so the system is stable some how? I have just installed a "AMD Phenom II X4 965 3.4Ghz Black Edition" cpu for your info.


Hi Dwarf,

I will take your advice onboard and read your suggested link.

Thanks guys - I hope you don;t mind me asking such amateur questions.

You're welcome.

As regards the question you posted above, at higher memory speeds timing becomes more and more of an issue. If you look closely at your motherboard, you will see that the tracks between the RAM slots and the memory controller, be it the Northbridge or the CPU itself, tend to zigzag a lot. This is to ensure that signals from/to the furthest slot arrive/leave at the same time as the nearest one (in between slots are similarly connected and arranged). Unfortunately, because of the physical constraints of the motherboard, there is a limit to this. In an ideal world, if you were able to straighten out all the data lines between the RAM slots and the controller, you would find that the lengths would be absolutely identical. In practice, you would find that the lengths could vary by upto 2mm or so. It doesn't sound much, but at higher and higher frequencies this variation in length becomes more and more significant. Not to mention the inductive and capacitive crosstalk that can occur at higher frequencies, a feature utilised in many older TV UHF tuner modules where the inductors were simply tracks on the PCB and capacitors (in the coupling sense) were 2 or more such tracks in parallel with each other. To overcome this, many motherboards will limit the maximum speed when more than a specified number of slots are used.

Also the current AMD CPUs have the memory controller in the CPU and is designed to run at 1333. Since you have a newer version of the CPU you may not have a problem. If you do you can try and change your memory to the slower 1333 speed. There are other tweaks that may work also but many people have no problems.

Jim

Hi dwarf/phoneman,
thanks once again for your input. I think what i will need to do is try and find a forum for my mobo and ask others what their performance is like with additional ram, if any of them use my cpu that is.

Thanks for educating me.

Regards